Placement of a hearing device inside the ear canal is generally desirable for various electroacoustic advantages such as reduction of the acoustic occlusion effect, improved energy efficiency, reduced distortion, reduced receiver vibrations, and improved high frequency response. Placement inside the ear canal may also be desirable for cosmetic reasons, with many of the hearing impaired preferring to wear inconspicuous hearing devices. A canal hearing device can be inserted entirely or partially inside the ear canal.
The ear canal is a hostile environment for hearing devices inserted within. Earwax and debris often plugs sound ports, and even migrates inside the hearing device causing damage to sensitive components inside, particularly the electronics and transducers, e.g., the microphone and receiver, inside. The transducers of conventional hearing devices typically degrade in audio characteristics over time from debris such as earwax and moisture. In order to combat the hostile environment of the ear canal, conventional hearing devices typically include a barrier for the protection of transducers from ear canal debris. Permanent and disposable barriers and filters are often used in conventional hearing devices. These types of barriers eventually become overwhelmed by the debris in the ear canal, which causes plugging of the sound ports or damage to components of the hearing device from debris ingress. Damage by debris is common in canal hearing devices, particularly in CIC types, because of the depth of insertion into the ear canal and the severity of the environment therein.